Treatment of hydrocarbon oil



Oct. l. 1940. s. ARMISTEAD, JR 2,216,683

TREATMENT OF HYDROCARBON OIL Filed sept. so, 1937 v 4Z' 601111,51? A.

INVENTOR GEO/ ARM/571590, .r/r.

ATTORNEY Patented Oct. l, 1940 n UNITED STATES TREATMENT OFHYD'ROC'ABBON OIL George Armistead, Jr., Scarsdale, N. Y., assignor toGasoline Products Company, Inc., Newark, N. J'., a corporation ofDelaware Application September 30, `1937, Serial No. 166,492

' 3 claims. (o1. 19e- 67) This invention relates to the art ofconverting higher boiling hydrocarbons into lower boiling hydrocarbons.L

According to my invention the heat necessary to effect the desiredextent of cracking of a heavy oil and drastic cracking ofa relativelyclean oil is supplied by burning a residual oil or the like and mixingthe hot products of combustion directly with the oils to be cracked soas to utilize a substantial part of the heat thus generated. One of thereasons why prior processes in which air is injected into a largebodygof oil in a large vessel have not been successful is because of theobjectionable deposition of coke. 'In one step of my process the oil andoxygen-containing gas are passed through a narrow and conned passageway,and in this way objectionable coking is rovercome as there is acontinualmovement of oil past the nozzle. My invention may also employan oxygen-containing gas richer in oxygen than air, in fact, pureoxygenitself and with the presence of fless inert diluent gas at thepoint of combustion, higher localized temperatures are obtained withconsequent improvement in oil de- 25. composition rate and character ofproducts.

In one form of the invention a heavy oil is burned with oxygen or withan oxygen-containing gas and the hot products of combustion, preferablyseparated from unburned heavy oil, are di- 30 rectly mixed with arelatively clean cil stock to be cracked to' raise the temperature ofthe clean oil stock to an active cracking temperature. The combinedstream yis then passed through'a cracking coil-or zone wherein the oilto be cracked is 35 maintained under superatmospheric pressure and ahigh temperature for a suicient time to effect n the desired cracking.

The stream of cracked products` leaving the cracking zone is then passed'under a lower pressure to an evaporator or separatingzoner where hotvapors are separatedfrom cracked residue. Before being passed to theevaporator, the stream of cracked products may be mixed with productscoming from another cracking zone as will be hereinafter described. Thehot vapors passupwardly inthe evaporator Lor-separating zone and arecontacted with a relatively heavy fresh charging oil, suchas reducedcrude oil, and in this way some of the hot vapors are condensed to forma heavy reux condensate and some of the lighter constituents of therelatively heavy oil are vaporized. t

The unvaporized fractions of the heavy charging oil and the heavy reiluxcondensate are collected and a portion thereof may be burned with oxygenor with an oxygen-containing gas, there being insuiiicient oxygen toconsume all of the oil. By this combustion the temperature of the heavyoil and reflux condensate is raised and the heavy oil and reuxcondensate are subjected to any degree of cracking varying from a mildconversion directed at the reduction of viscosity and formationv of gasoils from the residuals to the formation of a large yield of gasoline.The products of this treatment are discharged into a separator in whichkthey may be separated into vapors and a liquid residue. The vapors arepassed to the evaporator or separating zone above mentioned and theliquid residue under reduced pressure is mixed with the stream ofcracked products leaving the rst mentioned crackingV zone, the lattercombined stream also being introduced into the evaporator or separatingzone above described. However, they separator may be bypassed and allthe products of this treatment may be mixed with the cracked productsleaving the rst mentioned cracking zone and the combined stream thenpassed to the evaporator or separating zone.

The vapors remaining after contact with the, relatively heavy chargingoil are fractionated to separate a reflux condensate of the nature ofgasoil from vapors of the desired boiling'range. The

gas oil condensate thus separated'may form the feed stock to the cleanoil cracking zone hereinbefore mentioned. The vapors of the desiredboiling range arefurther treated to separate water and carbon dioxidefrom the gasoline product in any suitable manner. t

In the drawing I haveshown a diagrammatic flow sheetof apparatus adaptedfor practicing my invention.

Referring now t'o the drawing, the main parts of the apparatus comprisea combustion chamber or zo'ne Il), a cracking zone I2, another'cracking-zone I4, a combined evaporator and fractionating zone I6 and asecondary fractionating zone I8 which may-be of bubble towerconstruction. Pipe lines, pumps and other means are included whereby themethods of my invention may be carried out. The heavy oil collecting atthe bottom of the combined evaporator andfractionating zone I6 comprisescracked residue as will be later described in more detail. The crackedresidue is withdrawn throughline 22 and a portionthereof is passedthrough line 24 byv pump 26 and introduced into the combustion zone lilwhere it is' mixed and burned with oxygen or an oxygen-containing gasintroduced through .line 28 bypump 32. By regulating the opening ofvalve 33 any desired portion or all of the heavy cracked oil passingthrough line 22 may be pumped through line 24.

The heavy oil is burned during its passage through the combustion zoneID which is of proper construction to obtain the desired Contact betweenthe oil and oxygen or oxygen-containing gas and to -permit the requiredburning. Types of combustion zones may include nozzle mixers, refractorylined extended passages or the like. The proportion of oil to oxygen maybe such that a portion or all of the oil is consumed. The hot vapors andproducts of combustion thus formed may be passed through line 34 lto aseparator 35 wherein any liquid residue is yseparatedfrom hot productsof combustion and is withdrawn through line 35, the vaporous productsand gases of combustion being passed through line 38. However, theseparator 35 may be omitted, if desired, in which case all of theproducts leaving the com- .bustion zone IIJ are then passed through-line38. Where all the oil Iintroduced into zone Il! is burned, hightemperatures are obtained andit will be necessary to vconstruct theseparator 35, if one is used, and lines 34 and 38, as well as the zoneI0, of refractory material to withstand such high temperatures. yInaddition I may cool the hot products of combustion inthe zone I 0 byintroducing cool gases through line 39, the gases f.' being recoveredduring the operation of the process as will be later explained. Or theseparator 35, lines 34 and 38 and the zone I0 may be internallyinsulated to protectv the internal surfaces thereof from the hightemperatures.

A relatively clean oil stock such as condensate oil takenY from thebottom of the secondary fractionating zone I8, is passed throughfline 40by pump 4I and is admixed with the hot products of combustion passingthrough line 38 in order to immediately raise the clean oil stock to anactive cracking temperature. The heated oil' is then passed throughthecracking zone I2 preferably unred where it is maintained under hightemperature and high pressure conditions in order to effect the desiredcracking. The crackingzcne may alsolinclude a soaker 42 but this soakermay be of coil `constructionand form a continuation of the cracking coilor zone I2. In some instances it may be desirable toprovide a furnace orheater for the cracking coil or zone I2 andsoaker 42if a coil is used tosupplyadditional heat externally thereto. l

The stream of cracked products leaves, the cracknig zone through line 44having a pressure A reducing valve 46 and is preferably mixed withcracked products cor-ning from the othercracking zone or coil I4 laterto be described in `more detail. The combined stream including thecracked products from the crackingzone I2 is passed under lower pressureinto the evaporator or separating zone 52l of the combined evaporator`and fractionating tower I6 where a separation into hot vapors andcracked residue takes place. The cracked residue is withdrawn throughline 22 and may form part ofthe oil'which is burned in theV andfractionating tower I6 through line 60 in order to preserve the properquality of the vapors passing through line 6I. If desired, only part ofthe fresh feed may be introduced into the latter passes of the crackingzone I2 and the rest introduced into the combined evaporator andfractionating tower.

The unvaporized fractions of the heavy oil and the heaxy refluxcondensate are withdrawn from the trapout tray 56 fandl are. passed'through line 62 .by pump' 64.1 The stream` of oily passing through line62 is combinefd with oxygen or an oxygen-containing gas introducedthroughline 65 and a portion of the heavy oil is burnedin order` toraise the temperature of the unconsumed'heavy oil. The hot products ofvcombustion and'unconsumed he ated heavyl :oil are passed through thecoil or zone I4 maintained under appropriate cracking conditions toeffect the desired degree of` cracking of the oil. In the preferredmethod of operation the proportion of oxygen, the temperaturel and thetime of digest inthe zone I4 are controlled to give the greatestreduction in viscosity of the residual constituents of the feed and toproduce the greatest amount `of comparatively low boiling range gas oilsuitable for furthercracking or for withdrawal as a product Whileiit ispreferred to use thev coilA I4 which is no ,t' externally fired, in someinstances it may bedesirable to provide a furnace'or a heater` for thecoil vIII to supply additional heat externally thereto;H The coil I4 maybe used to viscositybreak heavy oils other than the Aheavy oil Jtakenfronrthe fractionating section 5,3.l v

`After passing through the zone orf coill I4, the

h ot products of combustionand cracked ,products may be passed throughline 66 to a separator 68 and a Acoolingroil may beintroduced throughline 59. In the lseparator 68 there is a separation into hot-vaporswhich. are passed through line I2 having pressure reducingvalve 'i3 intothe evaporator orseparating zone52of the combined evaporator andseparating ,tower I6, and liquid residue which is withdrawnffrom thebottom of the separator' v68` through lineI' byY pump '16. The liquidresidue may then be passed throughline 'I8 having a pressurel reducingvvalve 82 and mixed Withthe stream of cracked products leaving thecracking zone I 2 throug'hline 44 toeffect further Imild crackingjoryiscosity breaking o f theliquid residue..A This .latter combinedstream is then,v introduced'linto the evaporator or separating *zoney52l.ofggthe combined evaporator and ,fractionatingftower I6 wherein aseparation, into hottvapor's and cracked'residue occurs as hasbeen=above fdescribedLLines 66 and 18 are provided with Valves' sothattheseparator'BB*maybeby-passed in Whi'clievent the products lfromthe cracking coil`jI4-preferably quenched, are passed directly throughline, lI8 into evaporatorV 52. AThe separator 68 maybe provided with thenecessaryY internalfractionating equipment'lto serve'asan'efiicientfractionator for theproduction of vgas oil as'side streams,

such as at S3, for heating or Diesel oils or similar purposes. i f'Instead of passing all of theunvaporizedportions of the heavy oil andheavy reuxfco'n'densate throughline62, I may pass allor part thereofthrough'line 8 4 by pump 85"-and introduce the unvaporized portions ofthe heavy Voil and heavy reflux condensate into the latterpasses of thecracking zone orcoil I2,\or if desired, into the soaker 42. Byintroducing the heavy oil into the latter passes of cracking Zone orcoil I2 or into the soaker 42, the temperature of the `heavy oil israised to effect viscosity breaking thereof while the cracking of thevoil first introduced into the cracking zone I2 continues. v

The vapors remaining after contact Awith the fresh feed oil introducedintothe fractionating section 53 of the combined evaporator andfractionating tower I6 are passed through line 6I into the bottomportion of the secondary fractionating zone I8 wherein they passupwardly and are subjected to further fractionation by means of coolingapplied to the top of the secondary fractionating zone I8. During thisfractionation the fresh gas oil constituents distilled from the freshfeed in fractionating section 53 along withunconverted gasoilcollect atthe bottom of the secondary fractionating zone I8 and form the stockwithdrawn through line and passed through the main cracking zone I2.Drawoi points'l and 88 may be provided to permit-the withdrawal of gasoil from the system for use as heating and Diesel oils or the like. V

The vapors of the desired boiling range leave the top of the secondaryfractionatingzone I8 through line 90, are condensed by passing throughcondenser 92 andthe distillate is collected in a receiver or drum 94.The distillate collected in the receiver or drum 94 comprises-gasolineand water which may be separated in any suitable mannen' Ythe waterbeing .drawn off through valved line 96 and the gasoline withdrawnthrough line 91.

through line 98 and are passed to a washing tower I III into whichwateror any other suitable solution or medium is introduced through line||2. YIn the case of Water the carbon dioxide present in the gases willbe dissolved and the solution of carbon dioxide is withdrawn from thebottom of the tower IIO through valved line II4. The remaining gases arepassed from the top of the tower I I0 through valved line I I6 and maybe passed to a suitable recovery plant for :the extraction of containedgasoline.-` All orf a portion of these gases leaving the top of towerIIII may be used for cooling by being introduced into ther combustionZone I0 through line 39 as above described. The use of comparativelypure oxygen for heating in the coil I4 and combustion zone I0 has theadvantage of producing no combustion products-other than carbon dioxideand water which can be readily separated out before the kremaining gasesgo to the recovery plant thus simplifying the stripping of the gases `inthe final steps of the process. y Y

A portion of the gasoline collected inthe receiver 94 may be passedthrough line ||8 by pump I I9 into the upper portion of the secondaryfractionating zone I8 as reflux. As additional refiux some of theliquidnear the top of the secondary fractionating zone .may bewithdrawnthrough line |20 by pump |22 and passed through heat exchanger |24 andthen returned to thetop of the secondary fractionating zone I8 throughThe gases which are not con-l densed leave the top ofthe receiver ordrum94v line |26. The 'heat exchanger |24 serves to preheat the fresh feedpassing throughfline 54 prior to its introduction intothe fractionatingsection 53 of the combined evaporator and fractionating tower I6. f

The fresh feed pump |32 and after beingpreheated in heat exchanger I24`is further preheated by vpassing through heat exchanger |34. The.preheated fresh feed is then passed through line 54 into thefractionating section53 lof lthe combined evaporator and fractionatingtower I6.

The part -of 'the cracked residue not used for burning in combustionzone I0 may be combined with the liquid residue passing through line 36from the `separator 35 and passed through heat exchanger |34 forpreheating the fresh feed. The combined residue is then passed throughcooler |36 and line |38 to a suitable` receiver. The pump 32 is providedto pump the oxygen or oxygen-containing gas through lines 28 and 65tothe combustion zone I0 and cracking coil I4. An example of a typicaloperation contemplated by my invention will now be given but Iam not tobe restricted thereto. `The fresh feed, such as reduced crude oil orother oil, preferably preheatedto a temperature of about 250 to 550 F.,is introduced into the top portion of the fractionating section 53 whereit contacts the hot vapors therein. The unvaporized fractions of theheavyoil and the heavy reflux condensate are withdrawn from the bottomof the fractionating section 53 at a temperature of about 700 to 800 F.,and are mixed with about 2.7 to 3.0 per cent by weight of oxygen orequivalent amount of oxygen-containing gas. A part of the heavy oilmixture is consumed bypassing through coil I4 and thev temperature ofthe unconsumed oil is raised sufficiently high to effect `mild crackingor viscosity lbreaking thereof. The mixture of hot combustion productsand unconsumed oil during its passage through the cracking zone or coilI4 is maintained -under superatmospheric pressure of about 100 to 1000pounds per sq. in. and a temperature of about 850 to 950 F. for asuflicient time to effect the desired extent of viscosity breaking ofthe oil.

If the unvaporized fractions of the heavy oil and heavy refluxcondensate collected on trapout tray 56 are passed through line 84 andthrough the latter passes of the cracking coil or zone I2 instead ofthrough the cracking zone I4, they are maintained undervsuperatmospheric pressure of about 400 -to 1000 pounds per sq. in. andat a temperatureof about 850 to 950 F. for a sufficient time to effectthe desired extentl of viscosity breaking thereof. A

' Cracked residue is withdrawn fromA the bottom ofthe evaporator orseparating zoner 52 of the combined evaporator andl fractionating towerI6 through line 22 and `a portion of this residue is partially orcompletelyburned in the combustion zone I0. The combined evaporator andfractionating tower I6 is pref erablytmaintained under` superatmosphericpressure, for example, about to 100 pounds. per sq. in. and the crack-edresidue under these Yconditions will be at a ternperatur'e of about '750to 850"v F. 'The desired portion ofthe cracked residue is mixed withabout 320% by weight of oxygen or equivalent amount of oxygen-containinggas and burned by passing through the combustion zone'l. The proportionscf oxygen or oxygen-containing gas and oil to be burned are preferablychosen so that sube, stantially all of. the crackedresidue will be'con.A

is passed through line 54 byv sumed during the burning. The crackedresidue Withdrawn from the evaporator 52 is at a relatively hightemperature and when it is combined with the oxygen or oxygen-containinggas, an instantaneous rise in temperature results, the effect of whichon the oil may be regulated by the size of the contacting zone as wellas the proportion of oil and oxygen. By using a smaller proportion ofthe oxygen-containing gas, only apart of the cracked residue will beconsumed and a lower temperature will be obtained.

After passage through the combustion zone I0 the products are passed tothe separator 35 Where vapors are separated from any liquid residue. Theliquid `residue is withdrawn through line 36 and is preferablyintroduced into the line 22 subsequent tothe point of withdrawal of aportion of the cracked residue through line 24. The vapors and hotcombustion products from the separator 35 at a temperature of about1500n to 4000c F.`are passed to the cracking zone or coil I2 where theyare mixed with the oil to be cracked.

The oil to be cracked is preferably the condensate oil withdrawn fromthe bottom of the secondaryfractionating zone I3 which is preferablymaintained und-er superatmospheric pressurefor example, about 50 to 100pounds per sq. in. and under these conditions the condensate oil will beat a temperature of about 550 to '700 F. The condensate oil to becracked and the hot vapors and combustion products leaving the separator,35 are adrnixed and the mixture is passed through the cracking zone I2which is maintained under a high temperature of about 825 to 1125 F. anda superatmospheric pressure of about 400 to 1000 pounds per sq. in. forthe desired time to effect the desired cracking of the oil.

'Ihe stream of cracked products is passed from the cracking zone I2through the soaker 42 into the separating zone 52 of the combinedevaporator and separating tower I6 which is under less pressure than thecracking zone I2 and where a separation into vapors and cracked residuetakes place. Before being introduced into the evaporato-r or separatingzone 52, the stream of cracked products from the cracking zone I2 may bemixed with the cracked products leaving the cracking zone I4, or thestream may be passed directly to the evaporator or separating zone 52.

Known processes in which a large body of oil in a vessel is treated withair are subject to the objection that coking occurs around the airnozzles mounted within the body of oil. After building up to a certainheight, pieces of the deposited carbon break off and deflect the airstream. The coke then burns and in this burning localized overheatingoccurs which is a hazard to the apparatus in which the process iscarried out. According to my process the burning of the oil takes placein a confined passageway such as a coil, for example, and objectionablecoking with its accompanying hazards is overcome.

In my invention aircr oxygen-containing gas or the like is introducedinto a stream of oil passing through the zone I4 by a nozzle so thatthere is a continuous passage of oil past the nozzle and thepassagewayis kept open by the continuous movement of the oil through the zone. Ifthere is any coke formation, it will not be su'icient to stop or impairthe operation of the process and ifany pieces of the coke break off theyWill be carried along with the oil stream and will not cause localoverheating of a portion of the apparatus. Generally, exceedingly high.temperatures will be obtained-in combustion zone I0 and there will be no objectionable deposition of coke therein. The use of anoxygen-containing gas richer in oxygen than air, moreover, has atendency to prevent the objectionable deposition of coke because of highcombustion temperatures which prevail and form the complete andinstantaneous burning of the oil without the formation ofdecompositionintermediates which are the source of coke formation. A

From the foregoing lit will be apparent that I have disclosed a. newprocess for converting oils which overcomes the objectionable featuresof prior known processes.

While I have described a particular embodiment of my invention, it is tobe expressly understood that my invention is not restricted thereto, andvarious modifications and adaptations thereof may be made Withoutdeparting from the spirit of my invention.

I claim:

1. A process for converting higher boiling hydrocarbons into lowerboiling products that comprises separating resulting cracked products ofthe process into vapors and residue in a separating zone, passingresultant separated vapors to a fractionating vzone into which chargingstock is introduced and wherein fractionation takes place to formseparated vapors and a fraction comprising unvaporized charging stockand reflux condensate, passing the separated vapors to a secondaryfractionating zone wherein the vapors are subjected to fractionation toform a secondary reflux condensate, withdrawing separated' residue fromthe separating zone conducting residue so withdrawn to a contactingzone, introducing an oxygen-containing gas into said `contacting zone toeffect combustion of at least a portion of the cracked residue,comprising unvaporized charging stock and reflux condensate to aflattersection of said elongated passageway to thereby subject said fraction tocracking, and directing resultant cracked products intoA said separatingzone.

2. A process for converting higher boiling hydrocarbons into lowerboiling products that comprises separating resulting cracked products ofthe process into vapors and residue in a separating zone, passingresultant separated vapors to a fractionating zone Vinto which chargingstock is introduced and wherein fractionation takes place to formseparated vapors and a fraction comprising unvaporized charging stockand reflux condensate, withdrawing separated residue from the separatingzone, conducting residue so withdrawn to a contacting zone,introducingan oxygen-containing gas into said contacting zone to effectcombustion of at least a portion of the cracked residue, combiningresultant gaseousl productsvof combustion with condensate oil to becracked and passing the mixture through an elongated passageway ofrestricted cross section maintained under superatmospheric pressure tothereby subject the condensate oil to cracking temperature and effectconversion into lower boiling products, introducing said fractioncomprising unvaporized charging stock and reflux condensate to a lattersection of said elongated passageway to thereby subject said fraction tocracking and directing resultant cracked products into said separatingzone.

3. A process for converting higher boiling hydrocarbons into lowerboiling products that comprises separating resulting cracked products ofthe process into vapors and residue in a separating zone, passingresultant separated vapors to a fractionating Zone wherein the vaporsare subjected to fractionation to separate out a condensate, withdrawingseparated residue from the separating Zone, conducting residue sowithdrawn to a contacting Zone, introducing an oxygen-containing gasinto said contacting Zone to elct combustion of at least a portion ofthe cracked residue, combining resultant gaseous products of combustionvwith said condensate and passing the mixture through an elongatedpassageway of restricted cross section maintained under superatmosphericpressure to thereby subject the condensate to cracking temperature andeiect conversion into lower boiling products, introducing a residualstock to a latter section of said elongated passageway to therebysubject it to cracking and directing resultant cracked products into therst mentioned separating zone.

GEORGE ARMISTEAD, JR.

